661289 has 6 divisors (see below), whose sum is σ = 682794. Its totient is φ = 640080.

The previous prime is 661267. The next prime is 661321. The reversal of 661289 is 982166.

It can be written as a sum of positive squares in only one way, i.e., 403225 + 258064 = 635^2 + 508^2 .

It is not a de Polignac number, because 661289 - 2¹² = 657193 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661259) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5144 + ... + 5270.

It is an arithmetic number, because the mean of its divisors is an integer number (113799).

2⁶⁶¹²⁸⁹ is an apocalyptic number.

It is an amenable number.

661289 is a deficient number, since it is larger than the sum of its proper divisors (21505).

661289 is an equidigital number, since it uses as much as digits as its factorization.

661289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 295 (or 168 counting only the distinct ones).

The product of its digits is 5184, while the sum is 32.

The square root of 661289 is about 813.1967781540. The cubic root of 661289 is about 87.1225208173.

The spelling of 661289 in words is "six hundred sixty-one thousand, two hundred eighty-nine".